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United States Patent | 5,026,148 |
Wen ,   et al. | June 25, 1991 |
A multiple quantum well photodetector structure has superlattice which absorbs radiation polarized non-parallel to the superlattice during a first pass. Non-absorbed radiation polarized parallel to the superlattice is reflected back into the superlattice at a cross-angle to its incident angle, with its polarization shifted to a substantially non-parallel angle to the superlattice. At least part of this radiation is absorbed during its second pass through the superlattice, thereby increasing the efficiency of the device. An optical back grating is used to perform the cross-angle reflection, and a front grating may also be used to shift an incoming beam which is initially normal to the superlattice to an angle at which part of the beam is absorbed. The front grating is at a cross-angle to the back grating to enable a cross-angular shift by the back grating.
Inventors: | Wen; Cheng P. (Mission Viego, CA); Wu; Chan-Shin (Torrance, CA); Sato; Robert N. (Palos Verdes Estates, CA) |
Assignee: | Hughes Aircraft Company (Los Angeles, CA) |
Appl. No.: | 457207 |
Filed: | December 26, 1989 |
Current U.S. Class: | 359/483; 257/E31.033; 257/E31.128; 257/E31.13; 359/248 |
Intern'l Class: | G02B 005/30 |
Field of Search: | 350/370-378,355,356,394,395,162.23,164,96.13,386,388,389 372/50,45 357/16,18 |
4025939 | May., 1977 | Aiki et al. | 357/18. |
4525687 | Jun., 1985 | Chemla et al. | 357/16. |
4915482 | Apr., 1990 | Collins et al. | 350/355. |
Foreign Patent Documents | |||
0249645 | Dec., 1987 | EP. |
"Physics and Application of Quantum Wells in Waveguides", J. S. Weiner, SPIE, vol. 578, Integrated Optical Circuit Engineering II (1985), pp. 116-121. |